PVD coatings different color each batch!

mettlesmith · Jul 22, 2008

Hi there, I have PVD coating done by a company in Ontario that boasts full process control for repeatable thickness and properties, yet every time I get a batch of parts done by them the color is slightly different. What could cause this variation? ZrN coatings are sometimes a rich lemon yellow (what I want) and other times pale silvery/gold (not good). Is there something I can suggest to them to get more consistency? I need both wear resistance and color quality. Thanks for any help.

davidmoul · Jul 23, 2008

there is a problem of process repetability. The point is that the temperature into the batch must vary from one batch to another one. Do you know if they have a strict procedure to arrange workpieces into the batch? Are they always reparted into the same configuration? Is there always the same quantity of pieces into the batch?

all conditions should always be the same.

What kind of batch are they using?

mettlesmith · Jul 23, 2008

Okay, so does this mean that chamber temperature is the main factor in color repeatability? I was told variations in surface appearance are due to eddies in the gas flow or variation in current density from different loads in the chamber. Is this correct, and what role does temperature play?

Thanks for trying to help me understand this process more fully. A few years into the research and development of my product and I still don't fully understand the variables.

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PVD coatings different color each batch!

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